The present proposal outlines a program of research in developmental clinical psychology to examine the development of the preschool child's competence in solving problems with peers from ages three to six. The three most important objectives of the research are (I) to document a general developmental transition in children's thinking about human behavior and conflict resolution over this age range, (II) to relate variation in problem-solving thinking to variation in children's behavioral strategies for establishing and maintaining dyadic interactive episodes with peers, and (III) to explore the interrelationships between such cognitive and behavioral problem-solving skills and the social outcomes the child receives from peers in daily classroom interaction. Subgoals of the project within these general aims are to extend our understanding of the usefulness of the Preschool Interpersonal Problem-Solving Test as a measure of social adjustment for this age group and to assess how well the sampled cognitive and behavioral measures discriminate between poor and adequate social integration and social assertiveness in the preschool classroom. The interrelationships among the controlled cognitive measures and the dyadic and group observational measures of spontaneous interaction will be explored through multivariate statistical analysis, including factor analytic, multiple regression and discriminant function analyses. No research to date has examined early social interaction with an emphasis on how these three levels of process interrelate to guide adaptive social interaction. The achievement of a description of the social competencies of the preschool years and of the developmental processes supporting these competencies is currently an important priority for the effective design and evaluation of preventative family support services and, ultimately, for the effectiveness of all of our child-rearing institutions in fostering the social development of young children.